Near-Field Radiative Heat Transfer between Black Phosphorus Sheets via Anisotropic Surface Plasmon Polaritons

Abstract

Black phosphorus (BP), a novel natural two-dimensional layered material with intrinsic in-plane anisotropy, has been attracting significant research attention due to its outstanding electronic and optical properties and tunable bandgaps. Here, an enhancement of near-field radiative heat transfer (NFRHT) arising from a coupling of anisotropic surface plasmon polaritons (SPPs) between two layered BP sheets is demonstrated. The coupling of SPPs along armchair and zigzag directions dominate the NFRHT at near-infrared and mid-infrared frequencies, respectively. The dependence of NFRHT on the number of layers as well as the electron density of BP is then analyzed. It is found that at a small gap size the NFRHT between BP sheets with more number of layers and a higher electron density is lower. While this trend is reversed at a large gap size. Finally, the possibility of using BP to modulate the NFRHT by the mechanical rotation is explored. It is shown that the rotated system exhibits a nonmonotonic dependency of its heat transfer coefficient on the rotation angle, which has never been noted in the noncontact heat exchanges at nanoscale before. This work opens the possibility to apply BP-based materials for active thermal management at the nanoscale.

The Optical Properties and Plasmonics of Anisotropic 2D Materials

“…Because of their unique plasmon dispersion, the hyperbolic plasmons can propagate in a certain direction with a large density of states and higher filed confinement, leading to applications of spontaneous radiation enhancement, hyperlens, negative index materials, and thermal management . Many of these have been realized in hyperbolic metasurfaces, created by artificial subwavelength structuring from visible to microwave frequency ranges .…”

Nonreciprocal radiative heat transfer between two planar bodies

“…Understanding radiative heat transfer [1][2][3] is essential in many applications ranging from radiative cooling [4][5][6] and thermal diodes [7] to thermal transistors [8][9][10][11] and thermophotovoltaic systems [12][13][14][15][16]. The majority of works investigating radiative heat transfer consider materials that satisfy Lorentz reciprocity [17][18][19][20][21][22][23][24][25][26][27][28][29][30]. On the other hand, it is known that breaking the constraint of reciprocity is necessary in order to reach the thermodynamic limit of thermal radiation harvesting [31][32][33].…”

Functional Mid‐Infrared Polaritonics in van der Waals Crystals

“…g) Ratio between the NFRHT and black body heat transfer rates as a function of d ; electron density n = 5 × 10 12 cm −2 . (f,g) Adapted with permission . Copyright 2018, American Chemical Society.…”

“…The nearfield density of photonic states dramatically increases due to the contribution of these high-k modes in a broad frequency regime. [119] Recently, Ge et al [110] and Zhang et al [118] theoretically investigated the NFRHT between the two suspended sheets of BP, and reported that the radiative heat flux can exceed the Planck's limit by 10 2 to 10 4 times for separation distance between 100 and 10 nm (Figure 6f,g). Liu and Zhang proposed periodic graphene ribbon arrays to induce hyperbolic modes and predicted a giant enhancement of the NFRHT by more than one order of magnitude.…”

“…(f,g) Adapted with permission. [118] Copyright 2018, American Chemical Society. h) FFRHT enhancement dominated by the TE-polarized guiding modes in the nanoribbons of graphene and BP.…”